On one of my carpc installations I was getting an annoying pop sound as the computer went into hibernation. What I have done was find a way to automatically turn off Amp Ctrl service before hibernation, and then resume after resuming from hibernation. Another words your amp is turned off before hibernation for a quiet exit.

First download this handy Hibernate Trigger program here:
http://www.rpi.edu/%7Edesimn/suspendtrigger/

Download and unzip my two programs into your c:\ampctrl_1.0 folder.

Configure Hibernate Trigger like so, and you're all good.